Back to EveryPatent.com
United States Patent | 5,568,606 |
Dobbek | October 22, 1996 |
A DASD array and method wherein spindles in the array are synchronized in speed of rotation and phase. The invention includes a plurality of spindles and at least one disk rotating around each spindle, wherein each disk comprises a plurality of tracks arranged into synchronization zones. The synchronization zones comprise a plurality of data sectors and an excess time period associated with each zone. The excess time period comprises raw and synchronization skew, wherein the skew is used to shift sector locations in response to excessive defects occurring in the synchronization zone on the disk. In this manner, the phase of the disks in the system are synchronized without consuming additional disk storage capacity. Each disk also contains skip profiles for controlling the distribution of unused sectors across the disks. The skip profiles are distributed to model the defect profile in the worst disk in the system. The skip profile and the skew are used in combination to shift sector locations back when defects are present.
Inventors: | Dobbek; Jeffrey J. (San Jose, CA) |
Assignee: | International Business Machines Corporation (Armonk, NY) |
Appl. No.: | 321142 |
Filed: | October 11, 1994 |
Current U.S. Class: | 714/8; 360/49; 711/4; 711/101; 711/112; 711/135; 714/42; 714/54 |
Intern'l Class: | G06F 009/00 |
Field of Search: | 395/600,404,428,439,462,182.06,183.18,185.07 364/DIG. 1 |
5237466 | Aug., 1993 | Glaser et al. | 300/73. |
5285436 | Feb., 1994 | Moribe | 369/158. |
5303097 | Apr., 1994 | Baba et al. | 360/73. |
5359611 | Oct., 1994 | Parks et al. | 371/404. |
5416648 | May., 1995 | Jeppson et al. | 360/73. |
5438464 | Aug., 1995 | Lewis et al. | 360/73. |
Legvold et al., R. F., IBM Technical Disclosure Bulletin, vol. 32, No. 11, pp. 85-92, Apr. 1990, "Record Mode Extension To Track Mode Caching ASD Subsystem". Craft, D. J., IBM Technical Disclosure Bulletin, vol. 35, No. 1B, pp. 193-194, Jun. 1992, "Improved High-Availability DASD Sub-System Configuration". |